Prior art fuel injectors have a valve guide bore in which a needle valve is reciprocated between open and closed positions with respect to an interior valve seat. The valve seat is spaced from an injector spray tip sack in communication with fuel holes for distributing the fuel. Such injector spray tips have a hemispherically configured sack region formed in the tip downstream of the seat to supply fuel to the spray holes when the needle valve is opened. Once the needle valve is closed, fuel contained in the sack region is no longer under pressure and will dribble from the spray holes during periods when no fuel should enter the combustion chamber. Consequently the combustion process may produce undesirable emissions, especially in diesel combustion processes. Anticipated emission regulations require reduction of such emissions.